The present invention is directed to bicycles and, more particularly, to an apparatus for reducing an engaging force of an engaging member in a bicycle component such as a shift control device.
Shift control devices are used to shift bicycle transmissions from one gear ratio to another. One type of shift control device shown in U.S. Pat. No. 5,400,675, for example, comprises first and second levers that operate a wire spooling device, wherein the first lever is moved from a rest position to an operating position to wind a transmission control wire around the wire spooling device, and the second lever is moved from a rest position to an operating position to unwind the transmission control wire from the wire spooling device. The wire spooling device comprises a cylindrical wire spooling member having a wire winding groove for winding and unwinding the transmission control wire, a plurality of drive teeth circumferentially disposed around the outer peripheral surface of the wire spooling member, and a plurality of positioning teeth also circumferentially disposed around the outer peripheral surface of the wire spooling member. The wire spooling member is biased in a wire unwinding direction by a return spring. A drive pawl is mounted to the first lever for pressing against one of the plurality of drive teeth in response to rotation of the first lever from the rest position to the operating position to thereby rotate the wire spooling member in a wire winding direction, and a positioning pawl selectively engages one of the positioning teeth to hold the wire spooling member in a desired rotational position. The positioning pawl is biased toward the positioning teeth by a pawl spring. The second lever is operated from the rest position to the operating position to selectively engage and disengage the positioning pawl to allow the wire spooling member to rotate in the wire unwinding direction in accordance with the biasing force of the return spring.
When the first lever is rotated to rotate the wire spooling member, the movement must overcome not only the biasing force of the return spring but also the frictional force of the positioning pawl caused by the pawl spring. The frictional force of the positioning pawl increases as the positioning pawl rises over the positioning teeth in response to rotation of the wire spooling member, and the rider must increase the force applied to the first lever accordingly.